Respuesta :
Answer:
1) [tex] CH_{4}(g) + 2O_{2}(g) --->CO_{2}(g) + 2H_{2}O(l)[/tex]
Enthalpy of combustion.
2) [tex]CH_{4}(g)----> C(g) + 4H(g)[/tex]
4x bond energy of C - H
3) [tex]C(graphite) + 2H_{2}(g)--->CH_{4}(g)[/tex]
enthalpy of formation of CH₄(g)
4) [tex]C(g) + 4H(g) ---> CH_{4}(g)[/tex]
- 4x bond energy of C - H
Explanation:
The enthalpy of reaction is the heat change during the reaction.
It can be:
a) Enthalpy of combustion : the heat change during complete burning of one mole of a substance in presence of oxygen.
[tex] CH_{4}(g) + 2O_{2}(g) --->CO_{2}(g) + 2H_{2}O(l)[/tex]
b) Enthalpy of formation: the heat change during formation of one mole of a substance from its constituent elements in their native state.
[tex]C(graphite) + 2H_{2}(g)--->CH_{4}(g)[/tex]
c) The difference in the bond energies of reactants and products.
[tex]enthalpy= sumofbondenergiesofreactants-sumofbondenegiesofproducts[/tex]
For:
[tex]C(graphite) + 2H_{2}(g)--->CH_{4}(g)[/tex]
[tex]Enthalpy=[0]-[4XbondenergyofC-H]=-4XbondenergyofC-H[/tex]
Another quantity that is equal to [tex]\rm \Delta H^{\circ}_{rxn}[/tex] is 1. enthalpy of combustion, 2. 4x bond energy of carbon-hydrogen bond, 3. enthalpy of formation and 4. -4x bond energy of CH bond.
What is enthalpy?
Enthalpy of the reaction is the total internal sum of the heat of the system reaction and the product of the volume and pressure of the system.
In the first reaction, [tex]\rm CH _{4} ( g ) + 2 O _{2} ( g ) \rightarrow CO _{2} ( g ) + 2 H _{2} O ( l )[/tex] the enthalpy for the combustion of the methane in the presence of oxygen is calculated. It gives the heat change during the burning.
In the second reaction, [tex]\rm CH _{4} ( g ) \rightarrow C ( g ) + 4 H ( g )[/tex], bond breaking will give the heat change as 4x bond energy of the carbon and hydrogen bond is endothermic.
In the third reaction, [tex]\rm C(graphite) + 2H_{2}(g) \rightarrow CH_{4}(g)[/tex], the enthalpy of the formation of methane will give the change in the enthalpy.
In the fourth reaction, [tex]\rm C(g) + 4H(g) \rightarrow CH_{4}(g)[/tex], the difference between the bond energies of the reactants and the products that are -4x bond energy of carbon and hydrogen will result in the enthalpy change.
Therefore, the bond of the combustion, the formation can be the component along with the enthalpy.
Learn more about enthalpy here:
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